The term smart card is used to describe a plastic card with one or two laminated sides, which usually carry some instructions and/or advertising printed thereon and/or certain safety features, for example a hologram, a magnetic strip, a photo of the card holder, or the like. A sort of module is embedded in the smart card. The module consists of an integrated semiconductor electronic circuit (chip) and, usually, of a contact-and-carrier plate carrying the chip. In the case of some cards, the wafer coacts with a plurality of surface segments to form electric contacts that are accessible from the outside. In the case of other cards, antennas are provided in the card for the non-contact exchange of information, for example of data. Smart cards of that kind are employed as telephone cards, authentication cards for mobile communications equipment, as check cards for money movements, as authorization cards for medical insurance schemes or the like, as right-of-access cards for buildings or parts of buildings, and for other purposes, such as the protection of goods. The user then introduces the smart card into, or moves it past, a card reader which thereby enters into communication with the electronic chip in the smart card via, corresponding contacts or antenna means. In the case of a telephone card or a check card, for example, it is then possible in this way to check the credit balance on an account, to determine the identity of a person or to exchange other data.
In order to enable smart cards to be simultaneously used as advertising vehicle, the smart cards preferably are produced in such a way that one or two films, preferably so-called labels, are employed to form one or both flat sides of the finished smart card. In this connection the term label is understood to describe a film with, preferably, one printed side. The label carries the advertising imprint, or the like. The imprint must be of high quality. It has been found that improved quality is achieved for the imprint when the film forming the label is printed before the smart card is produced.
For producing the smart card the label is introduced into the cavity of a plastic injection mold. For this purpose, the cavity exhibits a flat, cuboid shape, and the labels are placed on the flat surfaces of the cavity. It must be ensured in this connection that the labels are precisely positioned in the cavity and pressed against the surfaces of the cavity in order to allow the injection-molding process to be carried out smoothly.
Preferably, the same or a similar plastic material, such as polystyrene, propylene, ABS or polycarbonate, are used for the film of the label and the plastic material to be injected so as to ensure that an especially strong bond is achieved between the labels and the injected plastic material.
In this connection, the term "label" is used by way of example only. Generally speaking, both pre-cut and uncut films may be used within the scope of the present invention. The films may carry an imprint on one or both sides. They may be arranged on one or on more surfaces of the object, for example the smart card. In addition, other materials, such as transfer labels or transfer films may also be employed. The latter are provided with an imprint that is transferred to the object during the injection-molding process. After completion of the injection-molding process, the film is then removed and disposed of. Accordingly, films or labels may be used on one or more surfaces, or alternately with transfer labels or transfer films, or the latter may be used exclusively. And all these materials may be employed in pre-cut condition, or drawn off the roll.
The plastic material is conventionally injected into the cavity between the two labels through a feed slot provided in the area of one narrow end of the cavity.
Regarding the cross-section of the smart card, the rear surface is then formed by one of the labels. The front face, i.e. the view surface, comprises the contact and carrier wafer with the chip arranged behind it.
A method for producing a smart card has been known from EP-B1-0 399 868. In the case of this known method, the chip is at first mounted and wired on a metal strip, and is then embedded, together with the metal strip, in a plastic material so that one obtains a module which already exhibits a certain thickness. The module is configured in such a way that its thickness corresponds to the height of the cavity in the mold. Thus, when the mold is closed, a certain pressure is exerted upon the module whereby the latter is fixed in the cavity in a given position. Instead of using a pre-printed label, some embodiments of the known method make use of a picture-transfer film that is introduced into the mold cavity. The picture on the transfer film comes to adhere to the injected plastic material. After removal of the smart card from the mold, the imprint then remains of the plastic body, which does not contain any label, and the transfer film can be removed. According to certain variants of this production method, one or both flat sides of the smart card may be provided with an imprint with the aid of such films. On the other hand, the use of labels on one or both flat sides is likewise possible according to the known method. Since the known method provides that when labels are used the module is arranged on the inside of the label, the latter is cut out in the area of contact of the module so that the contacts of the module can be accessed from the flat side of the finished smart card.
It is a disadvantage of the known method that the proper positioning of the module in the mold cavity can be guaranteed only with difficulty. Specifically, the contact pressure required for fixing the module inside the cavity is produced only after closing of the mold so that there is a risk that the module may get displaced during the closing process of the mold.
Another disadvantage of the known method lies in the fact that when two labels and/or picture transfer films are used, two separate elements have to be introduced into the mold cavity. As the edges of smart cards have a length of a few centimeters only, the labels and/or the picture transfer films are relatively soft and instable because the label or films are extremely thin. Precise handling and positioning is difficult. This is true in particular when short cycle times are to be achieved, which are of course connected with rapid traveling speeds, accelerations and decelerations of the handling unit. Due to the resulting inertia forces, the relatively soft and instable labels and/or transfer films may then bend, fold over, or the like, so that there is a risk that an excessive percentage of waste may be produced.
Another disadvantage of the known method lies in the fact that after removal of the smart card from the mold, the material still has to be separated in the sprue area. The feed slot gives rise to a so-called film sprue that must be cut off after removal of the smart card from the mold. However, if such as sprue has to be cut off, there is always the risk that an inaccurate cutting line may be obtained which is extremely undesirable for the users of smart cards.
The invention claimed within the scope of the application also relates to plastic objects generally, to the extent comparable problems are encountered, even if this may not be specifically described herein by way of specific embodiments of the invention.
For example, it has been known in the production of plastic containers, i.e. small boxes, bowls or the like, or lids or inserts for such containers, to provide one side of such objects with a lamination. The respective side may be flat, dished, or bent in cylindrical shape. The lamination, which may, for example, contain an advertising imprint or instructions for use, may in this case likewise be formed by a label, i.e. an embedded plastic film.
Comparable problems are encountered also with plastic objects where mechanical, especially metallic objects are embedded by the injection-molding process, such as fasteners, reinforcing elements, hinges or electric/electronic elements, such as antennas, screenings, or the like.
In addition, it is generally a problem connected with the production of plastic objects by the injection-molding process that the indispensable gate points should be invisible on the finished product, if possible.
Now, it is the object of the present invention to improve a method and a semi-finished product of the before-mentioned kind in such a way that the described disadvantages are avoided. Specifically, the aim is to facilitate the inserting operation and to achieve shorter cycle times by avoiding the disadvantages connected with the rapid handling of soft, inelastic objects, specifically labels.